Generally, in a lens manufacturer, prescription data (i.e., ordering data) relative to spectacle lenses for a user (a person to wear spectacles) is obtained from a spectacles shop that is a client, and, based on the prescription data, a precursor lens that is commonly called a “round lens” is made and supplied to the spectacles shop. In the spectacles shop, the periphery of the precursor lens is cut to be fitted in a spectacle rim selected by the user so as to obtain a rim-shaped lens (note that there is also a case in which even this rim-shaped lens is processed by the lens manufacturer).
A technique in which the periphery of a precursor lens is cut so as to produce and leave only a rim-shaped lens from the precursor lens is well known as mentioned above, and Patent Document 1 is shown as one such example.
The term “rim-shaped lens” mentioned here denotes a lens obtained by processing a precursor lens so as to be shaped to be fitted in the inner peripheral shape of a spectacle rim. The term “round lens” is a commonly-used name for a precursor lens, derived from the fact that its external shape is formed in a circular or elliptical shape in consideration of handling.
Conventionally, the entire lens surface of a precursor lens (i.e., a round lens) has been processed according to processing data set for a rim-shaped lens. In other words, a part around a rim-shaped lens that is an unnecessary part to be cut in a step of the manufacturing process has also been processed based on processing data relative to the rim-shaped lens.